Baking is a science. This I came to learn while trying to understand the difference between baking powder and baking soda. You see how cakes and breads rise is all about how the rising agents react with the other ingredients one is baking with. That is the science behind baking. In short raising (or leavening) agents make your cakes and breads rise, your mousse and soufflé light and fluffy. The most common raising agents are: baking powder, baking soda, yeast and eggs.
Let me apologise early for the long sciency post, happy learning!!